Unable to Auto Boot Jetson TX2 When Powered on a Custom Board

Hello!

I have a Jetson TX2 that will not auto boot when provided power.
The TX2 sits in a custom board that should have auto boot enabled (CHARGER_PRSNT# is tied to GND).

I also have a Jetson TX2 Developer Board and have tried swapping over that unit, which does auto boot when power is connected.

Is there a bios or anything similar that must be set correctly for the auto boot to work?

Kind regards
Magnus

Hi, please check below topic and you can search auto power on in forum. In addition, there is P2597 board schematic in DLC for your reference.

Hi, Trumany!

Thanks for the reply, but I think you might have misunderstood my question.

If I’m understanding the post you’ve linked correctly, it is for enabling auto boot on the C02 board that comes with the dev kit?
That is not what I’m trying to do. Here are some more clarifications for my problem.

I have a custom board that houses a Jetson TX2, as well as other components, like an RFID-reader, a CSI/MIPI connector, and an audio DAC.
This board does not have a power switch and has been designed to utilize the auto boot functionality on the TX2.

I have a Jetson TX2 4GB that I flashed with Jetson 4.6, and it boots up on the C02 carrier board (after pressing the power button). However, it does not boot in my custom board, and I don’t have any power button to start it with.

Because I had already removed the dev kit TX2 I tried to connect that to my custom board, and it booted automatically once it got power.
Therefore I came to the conclusion that the board works fine, and that there is something missing on the TX2 4GB that I flashed.

I hope this makes my problem more clear!

-Magnus

Do you mean your TX2 module can auto boot with your custom board, but TX2 4GB module can’t? Can the TX2 4GB module auto boot on devkit?

Have you check the TX2 series product design guide in DLC? Auto-power-on part is same to TX2 and TX2 4GB as below description.

4.8 Optional Auto-Power-On Support
Jetson modules have optional support for Auto-Power-On. This allows the platform to power on when VDD_IN is first powered, instead of waiting for a power button press. Due to differences between the module designs, the mechanism for supporting Auto-Power-On for Jetson TX2/TX2 4GB is different from the one required for Jetson TX2i. These differences are described below. Note that the Auto-Power-On options described below would not work in designs that implement the “Power-on Type Detection & Control” circuitry implemented on the P2597_C02 design is used. This circuitry is not required for systems intending to support Auto-Power-On.
4.8.1 Jetson TX2/TX2 4GB Auto-Power-On Details
For Jetson TX2/TX2 4GB, to enable this feature, the CHARGER_PRSNT# pin should be tied to GND. To power the system on without a power button, a specific sequence is required between the time the VDD_IN power is connected and the CHARGER_PRSNT# pin on the module is driven low. The CHARGER_PRSNT# pin connects to the module PMIC and requires a minimum delay of 300ms from the point VDD_IN reaches its minimum level (5.5V) before it can be driven low. Jetson TX2/TX2 4GB includes circuitry on the module to support Auto-Power-On.

Yes, that is precisely what I mean.

Can the TX2 4GB module auto boot on devkit?

No, neither card can auto boot from the devkit, as I have not taken the necessary steps to enable that on the devkit carrier board.

Have you check the TX2 series product design guide in DLC? Auto-power-on part is same to TX2 and TX2 4GB as below description.

Yes. The design of the board was outsourced to a company in a neighboring city that designs PCBs regularly, and it should follow the design guide.

4.8.1 Jetson TX2/TX2 4GB Auto-Power-On Details
For Jetson TX2/TX2 4GB, to enable this feature, the CHARGER_PRSNT# pin should be tied to GND. To power the system on without a power button, a specific sequence is required between the time the VDD_IN power is connected and the CHARGER_PRSNT# pin on the module is driven low. The CHARGER_PRSNT# pin connects to the module PMIC and requires a minimum delay of 300ms from the point VDD_IN reaches its minimum level (5.5V) before it can be driven low. Jetson TX2/TX2 4GB includes circuitry on the module to support Auto-Power-On.

Does this mean that the CHARGER_PRSNT# (PIN A49 in the Jetson TX2 datasheet) has to be connected to GND from the start, or that it must start HI, then driven LO at least 300ms after VDD_IN hits 5.5V?

The following two sentences seem contradictory to me:

For Jetson TX2/TX2 4GB, to enable this feature, the CHARGER_PRSNT# pin should be tied to GND.

The CHARGER_PRSNT# pin connects to the module PMIC and requires a minimum delay of 300ms from the point VDD_IN reaches its minimum level (5.5V) before it can be driven low.

I’m by no means an expert when it comes to designing PCBs, but I do have a decent general knowledge when it comes to electronics, and I’m still confused by the wording in chapter 4.8.1.

Could you please elaborate/explain the auto boot sequence a bit more clearly for me?

I can see from the schematics of the board that it is designed with PIN A49 connected straight to GND, and I have also measured with the continuity check on a multimeter to confirm this.

As an aside, I can say that the RFID reader powers up when the TX2 4GB is on the board. The power management circuit on the board waits for the CARRIER_PWR_ON signal before transforming 12V to 5V and 3V3 (at least as far as I can understand from the schematic), so it looks like the TX2 4GB sends out the CARRIER_PWR_ON signal.

Thank you for your help so far!

-Magnus

Hi, again!

Sorry for asking twice, but I need clarification of the Design Guide.

I am, as stated above, somewhat confused about what is required to enable auto boot on a Jetson TX2 4GB.

The DG states

For Jetson TX2/TX2 4GB, to enable this feature, the CHARGER_PRSNT# pin should be tied to GND.

and

The CHARGER_PRSNT# pin connects to the module PMIC and requires a minimum delay of 300ms from the point VDD_IN reaches its minimum level (5.5V) before it can be driven low.

Does this mean

  1. That the CHARGER_PRSNT# pin can be tied to ground and does not need to be high at any point of the startup.

  2. That the CHARGER_PRSNT# pin must start high, and then driven low at least 300ms after minimum voltage (5.5V) has been established.

  3. Some other requirements that I have not thought about.

Does anyone know whether it is option 1 or 2 (or maybe 3)?

If it is option 2 (and maybe even 3), I need to have new boards made, and I would like to have that process started as soon as possible.

Thanks!

-Magnus

As said in the guide: Jetson TX2/TX2 4GB includes circuitry on the module to support Auto-Power-On. No need additional design on carrier board, just short the pin to ground.

That is good to know, but leads me back to my original question:
Why does the TX2 auto-boot, but the TX2 4GB does not?

On the board, the pin is shorted to ground, so that should be working on both of the Jetson units.

Are there any other reasons that one boots and the other doesn’t?

I can also add that the TX2 4GB has been flashed with stock JetPack 4.6 (L4T 32.6.1) through NVIDIA SDK Manager. I have made no changes to the Device Tree or kernel yet, though I do need to do some changes to at least enable the camera (IMX219) and do some pin muxing to be able to control some GPIO outputs.
The TX2 is the unit from the dev kit, and it was, as far as I know, pre-flashed when we got it. Therefore I do not know whether there are any changes to the Device Tree or kernel applied to it.

Thanks for your help so far, Trumany!

-Magnus